Starter equipped with a torque-limiter and damper device

Abstract

A motor-vehicle starter of the type including an electric motor ( 10 ) including a cylindrical casing ( 24 ) within which the crown ring ( 58 ), internally toothed, of a planetary gear train ( 22 ) is mounted so as to rotate, and of the type in which the crown ring ( 58 ) is linked in rotation to the casing ( 24 ) by way of a torque-limiter device which is interposed between the crown ring ( 58 ) and a lateral flange ( 30, 34 ) and which consists of at least one annular, friction side face ( 82, 84 ) of the crown ring ( 58 ) and of a disc ( 88, 89 ) which is linked in rotation to the casing ( 24 ), which are pressed axially and elastically against one another by an elastic element ( 112 ), wherein the disc ( 88, 89 ) is linked in rotation to the casing ( 24 ) by way of at least one damper block ( 92 ), elastically deformable, which absorbs mechanical energy when it is compressed, in such a way as to damp the variations in torque transmitted to the crown ring ( 58 ).

What is claimed is:  
     
       1. Motor-vehicle starter including an electric motor ( 10 ) an output shaft ( 16 ) of which rotationally drives a coaxial drive with the interposition a step-down planetary gear train ( 22 ) including a cylindrical casing ( 24 ) within which a crown ring ( 58 ), internally toothed, of the planetary gear train ( 22 ) is mounted so as to rotate, and of the type in which the crown ring ( 58 ) is linked in rotation to the casing ( 24 ) by way of a friction-type torque-limiter device which is interposed axially between the crown ring ( 58 ) and a lateral flange ( 30 ,  34 ) of the casing ( 24 ) and which consists of at least one annular, friction side face ( 82 ,  84 ) of the crown ring ( 58 ) and of a disc ( 88 ,  89 ) which is linked in rotation to the casing ( 24 ), which are pressed axially and elastically against one another by an elastic element ( 112 ) bearing axially on a reaction surface of the disc ( 88 ,  89 ), wherein the disc ( 88 ,  89 ) is linked in rotation to the casing ( 24 ) by way of at least one damper block ( 92 ), elastically deformable, which absorbs mechanical energy when it is compressed, in such a way as to damp the variations in torque transmitted to the crown ring ( 58 ). 
     
     
       2. Starter according to  claim 1 , wherein the resisting torque, due to the friction, between the reaction surface of the disc ( 88 ) and the elastic element ( 112 ) is less than the torque between the disc ( 88 ) and the crown ring ( 58 ). 
     
     
       3. Starter according to  claim 1 , wherein the casing ( 24 ), in its inner periphery, includes at least one axial recess ( 94 ) which is limited in angle, and in which is lodged at least one damper block ( 92 ). 
     
     
       4. Starter according to  claim 1 , wherein the disc ( 88 ,  89 ), at its outer periphery, includes at least one lug ( 98 ) which carries at least one compression tab ( 100 ) extending axially inside the an axial recess ( 94 ), and in that the damper block ( 92 ) is interposed in an angular way between at least one axial face of a compression tab ( 100 ) and an opposing side face of the axial recess ( 94 ). 
     
     
       5. Starter according to  claim 4 , wherein each said compression tab ( 100 ) is interposed in an angular way between two damper blocks ( 92 ) lodged in the same axial recess ( 94 ). 
     
     
       6. Starter according to  claim 5 , wherein the two damper blocks ( 92 ) are produced as a single damper element ( 93 ) including an axial slot ( 102 ) in which the compression tab ( 100 ) is accommodated. 
     
     
       7. Starter according to  claim 1 , wherein the disc ( 88 ,  89 ) is a component made from a cut-out and folded sheet metal with the lug ( 98 ) and the compression tab ( 100 ) produced as a single piece. 
     
     
       8. Starter according to  claim 4 , wherein each compression tab ( 100 ) is accommodated between two adjacent blocks ( 92 ) so as to interact with one or the other depending on the direction of rotation of the starter. 
     
     
       9. Starter according to  claim 1 , wherein the damper block ( 92 ) is made of elastomer material. 
     
     
       10. Starter according to  claim 1 , wherein the damper block ( 92 ) includes protrusions ( 122 ), on an axially oriented side face, so as to provide an energy-absorption capability which is variable as a function of the compression of the damper block ( 92 ) along a substantially tangential direction. 
     
     
       11. Starter according to  claim 1 , wherein several said damper blocks ( 92 ) are distributed over an angle. 
     
     
       12. Starter according to  claim 1 , wherein the damper blocks ( 92 ) are linked together so as to constitute an annular sleeve ( 106 ). 
     
     
       13. Starter according to  claim 1 , wherein an intermediate ring ( 90 ) is interposed between the disc ( 88 ) and the elastic element ( 112 ), and in that the resisting friction torque between the ring ( 90 ) and the disc ( 88 ) is less than the torque between the disc ( 88 ) and the crown ring ( 58 ). 
     
     
       14. Starter according to  claim 13 , wherein the ring ( 90 ) is prevented from rotating with respect to the casing ( 24 ).